What we affectionately call a "poor value spa"
Most popular hot tubs are constructed with this design.
Diagram 1:
Full foam design with the insulated cover in place.
With the cover in place, heat will stay inside the spa water.
The pumps and control box are located in a very small chamber on the side of the spa. This is seen on the left side of the diagram.
Heat from the pumps warm up this small space very quickly.
Vents are located in the small chamber to allow waste heat from the motors to escape.
This illustration shows the waste heat escaping from the vents on the side and rising upward into the atmosphere.
All of the heat in this type of spa comes from the hot tub's electric heater! 5.500 watts!!
This is why a full foam spa costs more to operate.
You might not do too badly if you never take the insulated cover off.
Problem is, people love to take the cover off and use their spas.
See diagram 2 below.
Diagram 2:
Full foam design with the insulated cover removed.
:
When the insulated cover is removed, heat rapidly rises upwards from the water into the atmosphere.
This illustration shows the waste heat also escaping from the vents and rising upward into the atmosphere.
As the water cools off, the electric heater will come on to re-warm the water. That is 5,500 watts!!
Again, All of the heat in the spa water comes from the hot tub's electric heater. That is 5,500 watts!!
Why is it so important, as the marketing experts suggest, to have such thick insulation on the bottom of the hot tub????
In a hot tub spa heat rises rapidly upwards...not sideways...or downward!!!!
Seven or more other design changes occur because of this "poor value" design.
1. When the small pump housing box overheats, the entire system is automatically shut off to prevent damage to the motors and controller. Heat buildup can happen quickly on a hot day as these pump motors can put out a lot of heat. Shutting down means no filtering, no water heating and no jets.
2. Because overheating is a real problem in this design, the designers decided to "fix" the problem. They started installing very small pumps that don't put out much heat. The circ pump is usually called the "tiny might" or some similar name and circulates only 6 gallons of water per minute for filtering. Less heat buildup certainly, but, insufficient filtering.
3. Because the therapy pumps put out even more waste heat, the designers again "fixed" the problem. You guessed it! Smaller therapy pumps were installed. Usually, less than 2.5 continuous HP each.
4. Because small therapy pumps are used, diverter valves must be used to provide acceptable jet pressure in each seat. The small pumps can only power the jets on one seat at a time.
5. Because diverter valves are used, the spa customer must constantly manipulate 2 or 3 diverter valves to get the water flowing to the seat of their choice. It is a fact that you can't run all of the jets at the same time in a "full foam/diverter valve" design.
6. Because small motors and pumps are used, the manufacturers save on the cost of building the spas. Smaller pumps are cheaper to install than larger pumps. If you look at the high prices of these "poor value" spas you will see that the cost savings are not passed on to the consumers. The manufacturer simply makes more money on each spa sale.
7. "Blowers" or what Haven Spas calls "Turbo air" is almost never found on these "poor value" spas. A special air pump blows air into the spa with air injectors and also special ports on the jets to boost the therapy effect. It is great when you really have sore muscles! Adding turbo air to the jets almost doubles the massage hydrotherapy coming from the jets. It is an absolutely wonderful feature to have on a hot tub. It is really a shame not to have a blower on your expensive spa.
8. But, blowers are left off of "poor value" spas because they end up blowing cool air into the spa water. This speeds up the cooling of the water. Cooling the water causes the 5,500 watt heater to come back on to keep the water warm.
9. Even though the builder saves a couple of hundred dollars by not installing a blower, the builder does not lower his price. Again, he just makes more money on the sale of each spa. He will try hard to convince you that you don't want a blower on your spa.
10. Then there are the leaks in a full foam spa. OMG! Read about repairing a leak on a full foam design spa HERE.